CN111411394A - Fracture-preventing kyropoulos preparation method of large-size sapphire single crystal - Google Patents
Fracture-preventing kyropoulos preparation method of large-size sapphire single crystal Download PDFInfo
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- CN111411394A CN111411394A CN202010268683.4A CN202010268683A CN111411394A CN 111411394 A CN111411394 A CN 111411394A CN 202010268683 A CN202010268683 A CN 202010268683A CN 111411394 A CN111411394 A CN 111411394A
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- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B17/00—Single-crystal growth onto a seed which remains in the melt during growth, e.g. Nacken-Kyropoulos method
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- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
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Abstract
The invention provides a fracture-preventing kyropoulos preparation method of a large-size sapphire single crystal, which comprises the steps of seed crystal pretreatment, charging, vacuum, heating and material melting, seeding, shouldering, constant-diameter growth, pulling-off, annealing, furnace shutdown, argon filling for cooling, furnace opening and the like.
Description
Technical Field
The invention relates to a preparation method of a sapphire single crystal, in particular to a fracture-preventing kyropoulos preparation method of a large-size sapphire single crystal.
Background
The mainstream sapphire crystal growth process in the world at present is a kyropoulos method, a pulling method, a guided mode method and a heat exchange method, and the sapphire crystal grown by the kyropoulos method accounts for about 70% of the current market. Growing large-size sapphire single crystals at low cost and high quality has become an urgent task at present. The growth of sapphire crystals by the kyropoulos method is developed to 300 kilograms from the original 45 kilograms to the present time, the growth period of the crystals with big kilograms is long, and the temperature gradient required by the growth of the crystals is large, so that seed crystals are easy to break in the growth and later annealing processes of the sapphire crystals, and the crystal ingots are cracked and scrapped.
For example, a method for preparing a large-size sapphire single crystal by kyropoulos disclosed in Chinese patent literature, wherein the publication number is CN106894087B, comprises the steps of charging, vacuum, heating and melting, seeding, shouldering, lifting a tray, growing at equal diameter, pulling off, annealing, stopping a furnace, cooling by filling argon gas, opening a furnace and the like, the invention ensures the single crystallinity of the crystal by the step of lifting the tray, effectively avoids the cracking of the crystal, and effectively inhibits the defects of small-angle grain boundary stress and the like, and the invention can only prepare products with the diameter of 350 × mm and the diameter of 120kg and the diameter of 350 × mm like the existing kyropoulos method, and if the products with the diameter of 200kg and the diameter of 380mm are required to be obtained, the invention and the existing kyropoulos method can easily break in the later process of crystal growth, thereby causing crystal scrapping.
Disclosure of Invention
The invention provides a fracture-preventing kyropoulos preparation method of a large-size sapphire single crystal, aiming at overcoming the problems that a large kilogram of sapphire crystals in the prior art is easy to fracture and the rejection rate of the crystals is high, and the sapphire crystals with high quality, low rejection rate, 200kg grade and phi 380 × 450 are prepared.
In order to achieve the purpose, the invention adopts the following technical scheme:
a kyropoulos preparation method of a large-size sapphire single crystal comprises the following steps:
(1) seed crystal pretreatment:
mechanically processing the seed crystal, then carrying out annealing process treatment, raising the temperature to 1680 ℃, keeping the temperature for 240min, and then reducing the temperature to room temperature;
(2) charging:
200-220kg of alumina is filled into a crucible in a single crystal furnace, and seed crystals are arranged on a pulling mechanism in the single crystal furnace;
(3) vacuumizing:
starting a vacuum-pumping system to vacuumize the single crystal furnace, and carrying out the next step when the vacuum degree in the single crystal furnace reaches 6.7 × 10-7 pa;
(4) heating and melting;
(5) seeding:
descending the seed crystal within 160 minutes of 120-160 minutes at the speed of 15-30mm/h through a pulling mechanism, continuing descending 10-20mm after the seed crystal contacts the liquid level of the melt, then rotating the seed crystal at the speed of 5-10rad/min through the pulling mechanism, ascending the seed crystal to be separated from the melt when the length of the seed crystal is rotationally cleaned to be 5-10mm, then descending the seed crystal to be contacted with the liquid level of the melt, wherein the distance between the contact position and the cold center of the liquid level of the melt is 0-40mm, then rotating the seed crystal at the speed of 5-10rad/min through the pulling mechanism and upwards pulling at the speed of 15mm/h per hour so as to start forming a crystal junction, and performing the next step when the length of the crystal junction is 60-80 mm;
(6) shouldering:
controlling the growth speed of the weight of the crystal to be 5g/h after the crystal is contacted with the liquid level of the melt, simultaneously pulling the crystal upwards at the speed of 15mm/h, and reducing the power at the descending speed of 30-50mw/h for shouldering;
gradually increasing the growth rate and simultaneously gradually decreasing the pulling rate as the weight of the crystal increases;
when the growth angle of the crystal is formed and accords with the growth angle of the sapphire kyropoulos method, the pulling speed is reduced from 5mm/h to 0.3mm/h, and the weight growth speed of the crystal is controlled to be 150-300g/h by changing the amplitude reduction of the power.
(7) Growing in an equal diameter way;
(8) pulling off;
(9) annealing:
reducing the heater power to 50kw at a power reduction speed of 500-;
(10) blowing out:
when the heating power of the heater is reduced to 1KW, the heater is turned off, and the vacuumizing system is turned off after 48 hours;
(11) filling argon for cooling;
(12) and (5) opening the furnace.
The method is characterized in that an annealing process is added after the seed crystal is mechanically processed, the stress in the seed crystal is effectively eliminated after the annealing process, the toughness of the seed crystal is increased, the seed crystal is effectively prevented from being broken at the later stage of the crystal growth, a constant temperature stage is added in the annealing process after the crystal growth is finished, the seed crystal breakage caused by the rapid temperature reduction in the annealing process is avoided, the single crystal property of the crystal is ensured through the rapid shoulder pulling and shouldering steps, the corresponding preparation parameters are improved, and the sapphire single crystal with the high quality of 200kg grade and the phi 380 × 450mm can be prepared.
Preferably, the step (1) further comprises: heating to 80 deg.C at a speed of 4 deg.C/min, heating to 100 deg.C at a speed of 1 deg.C/min, heating to 150 deg.C at a speed of 2.5 deg.C/min, heating to 1680 deg.C within 1680min, and holding at constant temperature for 240 min.
After a plurality of tests, the fracture resistance of the seed crystal is optimal through the annealing process at the speed and the temperature.
Preferably, the step (4) further comprises the steps of starting constant temperature when the heating device is heated at a pressure increasing speed of 1000-1500w/h until the power of the heating device reaches 82KW, continuing constant temperature for 2-4 hours when the alumina is melted to form the melt, then reducing the power of the heating device to 75KW at a pressure reducing speed of 500w/h, manually increasing and decreasing the power at a regulating amplitude of +/-50 mw after constant temperature for 1 hour, and carrying out the next step when the surface of the melt has crystal floating with the diameter of 10-20 mm.
Preferably, the step (7) further comprises controlling the growth rate of the crystal weight to be 300-500g/h when the weight of the crystal is 5-20KG, and controlling the growth rate of the crystal weight to be 800-1500g/h when the weight of the crystal is more than 20 KG.
Preferably, the step (8) further comprises adjusting the pulling rate to 5-15mm/h and the voltage drop rate to 500-100mw/h when the weight of the crystal is 240kg or more and the weight is not changed any more, and completely separating the crystal from the crucible within 40-120 minutes.
Preferably, the step (11) further comprises the steps of cooling the single crystal furnace by filling 3 times of argon, filling argon for the first time to 65psi 24 hours after stopping the furnace, filling argon for the second time to 45psi 28 hours after stopping the furnace, and filling argon for the third time to 0psi 32 hours after stopping the furnace.
Preferably, the step (12) further comprises opening an air inlet valve of the single crystal furnace after 8-10 hours of the last argon-filled cooling, opening a cover of the single crystal furnace when the internal pressure and the external pressure of the single crystal furnace are consistent, standing for 10-15 hours, and taking out the sapphire single crystal.
Preferably, in the step (2), the distance between the lower end surface of the seed crystal after installation and the top surface of the crucible is 50-55 mm.
The length of the crystal junction is controlled to be 50-55mm, the generation of dislocation and grain boundary can be caused when the crystal junction is too short, the gradient of the seed crystal is larger when the crystal junction is too long, and the seed crystal is easy to break in the later annealing process.
Preferably, the size of the seed crystal is 18 × 18mm or 20 × 20mm, the crystal direction is A direction, and the orientation precision is +/-0.1 degrees.
In the crystal of more than 200kg, the size of the seed crystal should not be too small, and when the external size is smaller, the seed crystal has certain possibility of breaking.
Preferably, the length of the seed crystal is 155mm to 165 mm.
The length of the seed crystal should not be too long, when the length is too long, the longitudinal temperature gradient of the seed crystal is too large, the seed crystal is easy to break, and the whole length should be controlled within 160 +/-5 mm.
Therefore, the method has the advantages that (1) the internal stress of the seed crystal is effectively eliminated through the annealing process of the seed crystal, so that the seed crystal can bear the growth of crystals with larger size, the seed crystal is not broken at the later stage of the growth of the crystals, the preparation of high-quality sapphire single crystals with the diameter of 200kg and the diameter of 380 × 450mm is guaranteed, (2) the seed crystal is not easy to break at the annealing stage through the constant temperature stage added in the annealing process after the growth of the crystals is finished, (3) the breaking condition of the seed crystal is further improved through controlling the size of the seed crystal, (4) the single crystallinity of the crystals is guaranteed through the step of rapidly lifting and shouldering, the cracking of the crystals is effectively avoided, and the defects of small-angle grain.
Detailed Description
The present invention will be described in detail with reference to specific examples.
Example 1
Preparing a sapphire single crystal according to the following steps:
seed crystal pretreatment:
mechanically processing the seed crystal, then carrying out annealing process treatment, namely heating to 80 ℃ at a speed of 4 ℃/min, then heating to 100 ℃ at a speed of 1 ℃/min, then heating to 150 ℃ at a speed of 2.5 ℃/min, then heating to 1680 ℃ within 1680min, keeping the temperature for 240min, then reducing the temperature to 1200 ℃, and finally reducing the temperature to room temperature within 7 min;
(2) charging:
210kg of alumina with the purity of 99.999 percent is loaded into a crucible with the diameter of 470mm in a single crystal furnace with the diameter of 1200mm, a seed crystal with the size of 20 × 20 × 160mm, the crystal direction of A and the orientation precision of +/-0.1 degrees is installed on a pulling mechanism in the single crystal furnace, and the distance between the lower end surface of the seed crystal and the top surface of the crucible after installation is 50 mm;
(3) vacuumizing:
starting a vacuum-pumping system to vacuumize the single crystal furnace, and when the vacuum degree in the single crystal furnace reaches 6.7 × 10-7pa, carrying out the next step;
(4) heating and material melting:
heating the crucible by a heater in a voltage increasing mode, starting to keep constant temperature when the power of the heater reaches 82KW at a voltage increasing speed of 1250w/h, continuing to keep constant temperature for 3 hours when alumina is formed into a melt, then reducing the power of the heater to 75KW at a voltage reducing speed of 500w/h, manually increasing and decreasing the power at an adjusting amplitude of +/-50 mw after keeping constant temperature for 1 hour, and carrying out the next step when the surface of the melt has 10 mm-diameter floating crystals;
(5) seeding:
lowering the seed crystal within 140 minutes at a speed of 21mm/h through a lifting mechanism, continuing to lower for 15mm after the seed crystal contacts the liquid level of the melt, then rotating the seed crystal at a speed of 8rad/min through the lifting mechanism, lifting the seed crystal to be separated from the melt when the length of the seed crystal is rotationally cleaned to be 8mm, then lowering the seed crystal to be in contact with the liquid level of the melt, wherein the distance between the contact position and the cold center of the liquid level of the melt is 20mm, then rotating the seed crystal at a speed of 8rad/min through the lifting mechanism and lifting the seed crystal at a speed of 15mm/h per hour to start forming a crystal junction, and performing the next step when the length of the crystal junction is 60 mm;
(6) shouldering:
controlling the growth speed of the weight of the crystal to be 5g/h after the crystal is contacted with the liquid level of the melt, simultaneously pulling the crystal upwards at the speed of 15mm/h, and reducing the power at the descending speed of 40mw/h for shouldering;
when the weight reached 100 g, the rate of growth of the weight was changed to 30g/h while pulling the crystals upward at a rate of 10 mm/h;
when the weight reached 300g, the rate of growth of the weight was changed to 50g/h while pulling the crystals upward at a rate of 8 mm/h;
when the weight reached 500g, the rate of growth of the weight was changed to 100 g/h while pulling the crystals upward at a rate of 5 mm/h;
when the weight reached 1000 g, the rate of growth of the weight was changed to 120 g/h while pulling the crystal upward at a rate of 5 mm/h;
when the weight reached 1500g, the rate of growth of the weight was changed to 150g/h while pulling the crystals upward at a rate of 5 mm/h;
when the growth angle of the crystal is formed and accords with the growth angle of the sapphire kyropoulos method, reducing the pulling speed from 5mm/h to 0.3mm/h, and controlling the weight growth speed of the crystal to be 200g/h by changing the amplitude reduction of power;
(7) and (3) isometric growth:
when the weight of the crystal is 5-20kg, controlling the growth rate of the weight of the crystal to be 400g/h, and when the weight of the crystal is more than 20kg, controlling the growth rate of the weight of the crystal to be 900 g/h;
(8) pulling off:
when the weight of the crystal is over 240kg and the weight is not changed any more, the pulling speed is adjusted to be 7mm/h, the voltage drop speed is adjusted to be 50mw/h, and the crystal is completely separated from the crucible within 80 minutes;
(9) annealing:
reducing the heater power to 50kw at a power reduction speed of 700mw/h, then keeping the constant temperature for 12h, reducing the heater power to 40kw at a power reduction speed of 450mw/h, then reducing the heater power to 20kw at a power reduction speed of 600mw/h, and finally reducing the heater power to 0w at a power reduction speed of 1000 mw/h;
(10) blowing out:
when the heating power of the heater is reduced to 1kw, the heater is turned off, and the vacuumizing system is turned off after 48 hours;
(11) filling argon for cooling:
stopping heating, filling argon for the first time of-65 psi within 24 hours, closing the valve before filling argon, and then closing the power supply of the molecular pump;
after the first argon filling is finished, closing the front-stage valve after 2 hours, and then closing the power supply of the mechanical pump;
stopping heating, and filling argon for the second time to 45psi for 28 hours;
stopping heating, and filling argon for the third time at 0psi for 32 hours;
(12) opening the furnace:
and (3) opening an air inlet valve of the single crystal furnace after the last argon filling gas cooling for 10 hours, opening a single crystal furnace cover when the internal pressure and the external pressure of the single crystal furnace are consistent, standing for 12 hours, and taking out to obtain the sapphire single crystal.
Example 2
Preparing a sapphire single crystal according to the following steps:
seed crystal pretreatment:
mechanically processing the seed crystal, then carrying out annealing process treatment, heating to 80 ℃ at the speed of 4 ℃/min, heating to 100 ℃ at the speed of 1 ℃/min, heating to 150 ℃ at the speed of 2.5 ℃/min, heating to 1680 ℃ within 1680min, keeping the temperature for 240min, reducing the temperature to 1200 ℃, and finally reducing the temperature to room temperature within 7 min.
(2) Charging:
200kg of alumina with the purity of 99.999 percent is loaded into a crucible with the diameter of 470mm in a single crystal furnace with the furnace chamber diameter of 1200mm, a seed crystal with the size of 18 × 18 × 155mm, the crystal orientation of A direction and the orientation precision of +/-0.1 degree is installed on a pulling mechanism in the single crystal furnace, and the distance between the lower end surface of the seed crystal and the top surface of the crucible after installation is 52 mm;
(3) vacuumizing:
starting a vacuum-pumping system to vacuumize the single crystal furnace, and when the vacuum degree in the single crystal furnace reaches 6.7 × 10-7pa, carrying out the next step;
(4) heating and material melting:
heating the crucible by a heater in a voltage increasing mode, starting to keep constant temperature when the power of the heater reaches 82KW at a voltage increasing speed of 1000w/h, continuing to keep constant temperature for 2 hours when alumina is formed into a melt, then reducing the power of the heater to 75KW at a voltage reducing speed of 500w/h, manually increasing and decreasing the power at an adjusting amplitude of +/-50 mw after keeping constant temperature for 1 hour, and carrying out the next step when the surface of the melt has crystal flotation with the diameter of 12 mm;
(5) seeding:
lowering the seed crystal within 120 minutes at a speed of 15mm/h through a pulling mechanism, continuing to lower for 10mm after the seed crystal contacts the liquid level of the melt, then rotating the seed crystal at a speed of 5rad/min through the pulling mechanism, lifting the seed crystal to be separated from the melt when the length of the seed crystal is rotationally cleaned to 5mm, then lowering the seed crystal to the liquid level contacting the melt, wherein the distance between the contact position and the cold center of the liquid level of the melt is 0mm, then rotating the seed crystal at a speed of 8rad/min through the pulling mechanism and lifting the seed crystal at a speed of 15mm/h per hour to start forming a crystal junction, and performing the next step when the length of the crystal junction is 66 mm;
(6) shouldering:
controlling the growth speed of the weight of the crystal to be 5g/h after the crystal is contacted with the liquid level of the melt, simultaneously pulling the crystal upwards at the speed of 15mm/h, and reducing the power at the descending speed of 30mw/h for shouldering;
when the weight reached 100 g, the rate of growth of the weight was changed to 30g/h while pulling the crystals upward at a rate of 10 mm/h;
when the weight reached 300g, the rate of growth of the weight was changed to 50g/h while pulling the crystals upward at a rate of 8 mm/h;
when the weight reached 500g, the rate of growth of the weight was changed to 100 g/h while pulling the crystals upward at a rate of 5 mm/h;
when the weight reached 1000 g, the rate of growth of the weight was changed to 120 g/h while pulling the crystal upward at a rate of 5 mm/h;
when the weight reached 1500g, the rate of growth of the weight was changed to 150g/h while pulling the crystals upward at a rate of 5 mm/h;
when the growth angle of the crystal is formed and accords with the growth angle of the sapphire kyropoulos method, reducing the pulling speed from 5mm/h to 0.3mm/h, and controlling the weight growth speed of the crystal to be 150g/h by changing the amplitude reduction of power;
(7) and (3) isometric growth:
when the weight of the crystal is 5-20kg, controlling the growth rate of the weight of the crystal to be 300g/h, and when the weight of the crystal is more than 20kg, controlling the growth rate of the weight of the crystal to be 800 g/h;
(8) pulling off:
when the weight of the crystal is over 240kg and the weight is not changed any more, the pulling speed is adjusted to 5mm/h, the voltage drop speed is adjusted to 75mw/h, and the crystal is completely separated from the crucible within 40 minutes;
(9) annealing:
reducing the heater power to 50kw at a power reduction speed of 500mw/h, then keeping the constant temperature for 8h, reducing the heater power to 40kw at a power reduction speed of 400mw/h, then reducing the heater power to 20kw at a power reduction speed of 500mw/h, and finally reducing the heater power to 0w at a power reduction speed of 1200 mw/h;
(10) blowing out:
when the heating power of the heater is reduced to 1kw, the heater is turned off, and the vacuumizing system is turned off after 48 hours;
(11) filling argon for cooling:
stopping heating, filling argon for the first time of-65 psi within 24 hours, closing the valve before filling argon, and then closing the power supply of the molecular pump;
after the first argon filling is finished, closing the front-stage valve after 2 hours, and then closing the power supply of the mechanical pump;
filling argon for the first time to 45psi 28 hours after stopping heating;
stopping heating, and filling argon for the first time at 0psi for 32 hours;
(12) opening the furnace:
and opening an air inlet valve of the single crystal furnace after 9 hours of the last argon filling gas cooling, opening a single crystal furnace cover when the internal and external pressures of the single crystal furnace are consistent, standing for 10 hours, and taking out to obtain the sapphire single crystal.
Example 3
Seed crystal pretreatment:
mechanically processing the seed crystal, then carrying out annealing process treatment, namely heating to 80 ℃ at a speed of 4 ℃/min, then heating to 100 ℃ at a speed of 1 ℃/min, then heating to 150 ℃ at a speed of 2.5 ℃/min, then heating to 1680 ℃ within 1680min, keeping the temperature for 240min, then reducing the temperature to 1200 ℃, and finally reducing the temperature to room temperature within 7 min;
(2) charging:
220kg of alumina with the purity of 99.999 percent is loaded into a crucible with the diameter of 470mm in a single crystal furnace with the diameter of 1200mm, a seed crystal with the size of 20 × 20 × 165mm, the crystal orientation of A direction and the orientation precision of +/-0.1 degree is installed on a pulling mechanism in the single crystal furnace, and the distance between the lower end surface of the seed crystal and the top surface of the crucible after installation is 55 mm;
(3) vacuumizing:
starting a vacuum-pumping system to vacuumize the single crystal furnace, and when the vacuum degree in the single crystal furnace reaches 6.7 × 10-7pa, carrying out the next step;
(4) heating and material melting:
heating the crucible by a heater in a voltage increasing mode, starting to keep constant temperature when the power of the heater reaches 82KW at a voltage increasing speed of 1500w/h, continuing to keep constant temperature for 4 hours when alumina is formed into a melt, then reducing the power of the heater to 75KW at a voltage reducing speed of 500w/h, manually increasing and decreasing the power at an adjusting amplitude of +/-50 mw after keeping constant temperature for 1 hour, and carrying out the next step when the surface of the melt has the floating crystal with the diameter of 20 mm;
(5) seeding:
lowering the seed crystal at the speed of 30mm/h within 160 minutes by a pulling mechanism, continuing to lower for 20mm after the seed crystal contacts the liquid level of the melt, then rotating the seed crystal at the speed of 10rad/min by the pulling mechanism, raising the seed crystal to be separated from the melt when the length of the seed crystal is rotationally cleaned to 10mm, then lowering the seed crystal to be contacted with the liquid level of the melt, wherein the distance between the contact position and the cold center of the liquid level of the melt is 40mm, then rotating the seed crystal at the speed of 10rad/min by the pulling mechanism and pulling the seed crystal upwards at the speed of 15mm/h per hour so as to start forming a crystal junction, and performing the next step when the length of the crystal junction is 80 mm;
(6) shouldering:
controlling the growth speed of the weight of the crystal to be 5g/h after the crystal is contacted with the liquid level of the melt, simultaneously pulling the crystal upwards at the speed of 15mm/h, and reducing the power at the descending speed of 50mw/h for shouldering;
when the weight reached 100 g, the rate of growth of the weight was changed to 30g/h while pulling the crystals upward at a rate of 10 mm/h;
when the weight reached 300g, the rate of growth of the weight was changed to 50g/h while pulling the crystals upward at a rate of 8 mm/h;
when the weight reached 500g, the rate of growth of the weight was changed to 100 g/h while pulling the crystals upward at a rate of 5 mm/h;
when the weight reached 1000 g, the rate of growth of the weight was changed to 120 g/h while pulling the crystal upward at a rate of 5 mm/h;
when the weight reached 1500g, the rate of growth of the weight was changed to 150g/h while pulling the crystals upward at a rate of 5 mm/h;
when the growth angle of the crystal is formed and accords with the growth angle of the sapphire kyropoulos method, reducing the pulling speed from 5mm/h to 0.3mm/h, and controlling the weight growth speed of the crystal to be 300g/h by changing the amplitude reduction of power;
(7) and (3) isometric growth:
when the weight of the crystal is 5-20kg, controlling the growth rate of the weight of the crystal to be 500g/h, and when the weight of the crystal is more than 20kg, controlling the growth rate of the weight of the crystal to be 1500 g/h;
(8) pulling off:
when the weight of the crystal is over 240kg and the weight is not changed any more, the pulling speed is adjusted to 15mm/h, the voltage drop speed is adjusted to 75mw/h, and the crystal is completely separated from the crucible within 120 minutes;
(9) annealing:
reducing the heater power to 50kw at a power reduction speed of 800mw/h, then keeping the constant temperature for 10h, reducing the heater power to 40kw at a power reduction speed of 500mw/h, then reducing the heater power to 20kw at a power reduction speed of 800mw/h, and finally reducing the heater power to 0w at a power reduction speed of 1500 mw/h;
(10) blowing out:
when the heating power of the heater is reduced to 1kw, the heater is turned off, and the vacuumizing system is turned off after 48 hours;
(11) filling argon for cooling:
stopping heating, filling argon for the first time of-65 psi within 24 hours, closing the valve before filling argon, and then closing the power supply of the molecular pump;
after the first argon filling is finished, closing the front-stage valve after 2 hours, and then closing the power supply of the mechanical pump;
filling argon for the first time to 45psi 28 hours after stopping heating;
stopping heating, and filling argon for the first time at 0psi for 32 hours;
(12) opening the furnace:
and opening an air inlet valve of the single crystal furnace after 8 hours of the last argon filling gas cooling, opening a single crystal furnace cover when the internal and external pressures of the single crystal furnace are consistent, standing for 15 hours, and taking out to obtain the sapphire single crystal.
Comparative example 1
210kg of alumina with the purity of 99.999 percent is loaded into a crucible with the diameter of 470mm in a single crystal furnace with the furnace chamber diameter of 1200mm, a seed crystal with the size of 20 × 20 × 160mm, the crystal orientation of A direction and the orientation precision of +/-0.1 degree is installed on a lifting mechanism in the single crystal furnace, the distance between the lower end surface of the seed crystal and the top surface of the crucible after installation is 52mm, wherein the seed crystal is not annealed after mechanical processing, and then the processing steps are as in example 1, the seed crystal is broken in the growing process of the sapphire crystal, the ingot is cracked and scrapped, and the sapphire single crystal cannot be manufactured.
Therefore, the seed crystal annealing treatment improves the seed crystal strength and is suitable for growing sapphire single crystals with larger weight and size.
Comparative example 2
200kg of alumina with the purity of 99.999 percent is loaded into a crucible with the diameter of 470mm in a single crystal furnace with the diameter of 1200mm in a furnace chamber, a seed crystal with the size of 16 × 16 × 160mm, the crystal orientation of A direction and the orientation precision of +/-0.1 degree is installed on a lifting mechanism in the single crystal furnace, the distance between the lower end surface of the seed crystal and the top surface of the crucible after installation is 50mm, wherein the size of the seed crystal is smaller than that in the embodiment 2, the seed crystal is annealed after being machined, the steps are as in the embodiment 2, the post-treatment steps are also as in the embodiment 2, the seed crystal is broken in the growing process of the sapphire crystal, the ingot is broken and scrapped, and the sapphire single crystal cannot be made into the sapphire crystal.
As can be seen, the external dimension of the seed crystal is smaller or the seed crystal is easy to break, and the size of the seed crystal is not less than 18 × 18 mm.
Comparative example 3
The process of comparative example 3 was substantially identical to that of example 2 except that the seed crystal had a length of 170mm, the seed crystal broke during the growth of the sapphire crystal, and the ingot was cracked and discarded, failing to produce a sapphire single crystal.
It can be seen that the length of the seed crystal should not be too long, so that the longitudinal gradient of the seed crystal is too large to easily cause breakage, and the overall length should be controlled to be 160mm + -5.
Comparative example 4
The process of comparative example 4 is substantially identical to that of example 3, except that the constant temperature stage in step (9) is eliminated, and it is found that breakage of the seed crystal occurs during annealing.
It can be seen that the constant temperature step in the annealing further eliminates the stress inside the seed crystal, preventing the seed crystal from breaking due to temperature changes during the annealing stage, which is an indispensable step.
The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.
Claims (10)
1. A fracture-preventing kyropoulos preparation method of a large-size sapphire single crystal is characterized by comprising the following steps:
(1) seed crystal pretreatment:
mechanically processing the seed crystal and then carrying out annealing process treatment, wherein the temperature is raised to 1680 ℃, the temperature is kept constant for 240min, and then the temperature is reduced to room temperature;
(2) charging;
(3) vacuumizing;
(4) heating and melting;
(5) seeding:
descending the seed crystal within 160 minutes of 120-160 minutes at the speed of 15-30mm/h through a pulling mechanism, continuing descending 10-20mm after the seed crystal contacts the liquid level of the melt, then rotating the seed crystal at the speed of 5-10rad/min through the pulling mechanism, ascending the seed crystal to be separated from the melt when the length of the seed crystal is rotationally cleaned to be 5-10mm, then descending the seed crystal to be contacted with the liquid level of the melt, wherein the distance between the contact position and the cold center of the liquid level of the melt is 0-40mm, then rotating the seed crystal at the speed of 5-10rad/min through the pulling mechanism and upwards pulling at the speed of 15mm/h per hour so as to start forming a crystal junction, and performing the next step when the length of the crystal junction is 60-80 mm;
(6) shouldering:
controlling the growth speed of the weight of the crystal to be 5g/h after the crystal is contacted with the liquid level of the melt, simultaneously pulling the crystal upwards at the speed of 15mm/h, and reducing the power at the descending speed of 30-50mw/h for shouldering;
gradually increasing the growth rate and simultaneously gradually decreasing the pulling rate as the weight of the crystal increases;
when the growth angle of the crystal is formed and accords with the growth angle of the sapphire kyropoulos method, reducing the pulling speed from 5mm/h to 0.3mm/h, and controlling the weight growth speed of the crystal to be 150-300g/h by changing the amplitude reduction of the power;
(7) growing in an equal diameter way;
(8) pulling off;
(9) annealing:
reducing the heater power to 50kw at a power reduction speed of 500-;
(10) blowing out the furnace;
(11) filling argon for cooling;
(12) and (5) opening the furnace.
2. The method for preparing a breakage-proof kyropoulos of a large-size sapphire single crystal as claimed in claim 1, wherein the step (1) further comprises: heating to 80 deg.C at a speed of 4 deg.C/min, heating to 100 deg.C at a speed of 1 deg.C/min, heating to 150 deg.C at a speed of 2.5 deg.C/min, heating to 1680 deg.C within 1680min, and holding at constant temperature for 240 min.
3. The method as claimed in claim 1, wherein the step (4) further comprises the steps of heating at a pressure increasing speed of 1000 and 1500w/h until the power of the heater reaches 82KW, keeping the temperature constant for 2-4 hours when alumina is melted to form a melt, then reducing the power of the heater to 75KW at a pressure reducing speed of 500w/h, manually reducing the power at a regulating amplitude of ± 50mw after the temperature is maintained for 1 hour, and performing the next step when the surface of the melt has a diameter of 10-20 mm.
4. The breakage-proof kyropoulos production method of a large-sized sapphire single crystal as claimed in claim 3, wherein said step (6) further comprises, when the weight reaches 100 g, changing the growth rate of the weight to 30g/h while pulling up the crystal at a rate of 10 mm/h;
when the weight reached 300g, the rate of growth of the weight was changed to 50g/h while pulling the crystals upward at a rate of 8 mm/h;
when the weight reached 500g, the rate of growth of the weight was changed to 100 g/h while pulling the crystals upward at a rate of 5 mm/h;
when the weight reached 1000 g, the rate of growth of the weight was changed to 120 g/h while pulling the crystal upward at a rate of 5 mm/h;
when the weight reached 1500g, the growth rate of the weight was changed to 150g/h while pulling the crystal upward at a rate of 5 mm/h.
5. The method as claimed in claim 1, wherein the step (7) further comprises controlling the growth rate of the crystal weight to be 300-500g/h when the weight of the crystal is 5-20KG, and controlling the growth rate of the crystal weight to be 800-1500g/h when the weight of the crystal is greater than 20 KG.
6. The method for preparing a breakage-proof kyropoulos of a large-sized sapphire single crystal as claimed in claim 1, wherein the step (8) further comprises adjusting the pulling rate to 5-15mm/h and the voltage drop rate to 500-100mw/h when the weight of the crystal is 240kg or more and the weight is not changed any more, and completely separating the crystal from the crucible within 40-120 minutes.
7. The method for preparing a breakage-proof kyropoulos of a large-sized sapphire single crystal as claimed in claim 1, wherein the step (11) further comprises the steps of cooling the single crystal furnace by 3 times of argon filling, filling argon for the first time to 65psi 24 hours after the furnace is stopped, filling argon for the second time to 45psi 28 hours after the furnace is stopped, and filling argon for the third time to 0psi 32 hours after the furnace is stopped.
8. The breakage-proof kyropoulos production method of a large-size sapphire single crystal as claimed in any one of claims 1 to 7, wherein in the step (2), the distance between the lower end face of the seed crystal after installation and the top face of the crucible is 50 to 55 mm.
9. The breakage-proof kyropoulos production method of a large-size sapphire single crystal as claimed in any one of claims 1 to 7, wherein the size of the seed crystal is 18 × 18mm or 20 × 20mm, the crystal orientation is A direction, and the orientation precision is ± 0.1 °.
10. The method for preparing a breakage-proof kyropoulos of a large-size sapphire single crystal as claimed in any one of claims 1 to 7, wherein the length of the seed crystal is 155mm to 165 mm.
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| WO2011027992A2 (en) * | 2009-09-05 | 2011-03-10 | 주식회사 크리스텍 | Method and apparatus for growing a sapphire single crystal |
| CN104911708A (en) * | 2015-06-15 | 2015-09-16 | 哈尔滨奥瑞德光电技术股份有限公司 | Growth method for preparing square sapphire crystal by Kyropoulos process |
| CN104975343A (en) * | 2015-06-04 | 2015-10-14 | 哈尔滨工业大学 | Method for improving quality of diamond seed crystal with hydrogen plasma multiple etching/annealing cyclic process |
| CN106894087A (en) * | 2017-04-21 | 2017-06-27 | 青海铸玛蓝宝石晶体有限公司 | A kind of bubble life preparation method of large-size sapphire single-crystal |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| WO2011027992A2 (en) * | 2009-09-05 | 2011-03-10 | 주식회사 크리스텍 | Method and apparatus for growing a sapphire single crystal |
| CN104975343A (en) * | 2015-06-04 | 2015-10-14 | 哈尔滨工业大学 | Method for improving quality of diamond seed crystal with hydrogen plasma multiple etching/annealing cyclic process |
| CN104911708A (en) * | 2015-06-15 | 2015-09-16 | 哈尔滨奥瑞德光电技术股份有限公司 | Growth method for preparing square sapphire crystal by Kyropoulos process |
| CN106894087A (en) * | 2017-04-21 | 2017-06-27 | 青海铸玛蓝宝石晶体有限公司 | A kind of bubble life preparation method of large-size sapphire single-crystal |
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